Higher anxietylevels may help elderly women live longer, but may harm older men, U.S. research shows.

A team at the Cleveland Clinic and Case Western Reserve University followed 1,000 seniors in three Florida retirement communities for up to 15 years.

They found that women with higher levels of anxiety at the start of the study lived longer than others. Year-to-year changes in anxiety levels didn't appear to affect women's survival, either.

In contrast to women, men with higher anxiety levels at the start of the study were more likely to die earlier, the researchers said.

"Our research indicates that anxiety may have a protective effect on women, possibly causing them to seek medical attention more frequently than men," Dr. Jianping Zhang, of the department of psychiatry and psychology at the Cleveland Clinic, said in a prepared statement. "In contrast, increasing anxiety over time is more detrimental to men. Additional research is needed to better understand the mechanisms and effects of anxiety in men and women."

The study is noteworthy due to the large amount of data collected over a long period of time, noted co-researcher Dr. Leo Pozuelo, who is also in the department of psychiatry and psychology at the Cleveland Clinic.

"Baseline higher anxiety could have led the female study participants to be more active and health-conscious," Pozuelo said in a prepared statement. "We are not certain of the absolute connection between anxiety and mortality, but this data set shows there may be a gender difference."